The present invention relates generally to repair stands or fixtures for temporarily bracing miscellaneous workpieces or devices. More specifically, the present invention relates to vises or stands for temporarily servicing gas meters during maintenance, repair or testing. The invention is believed best classified in U.S. utility class 29, subclass 281.4.
"Dry" or Bellows-type gas meters are widely used in domestic and commercial environments. Such meters typically comprise an outer, box-like housing having at least one gas inlet and one gas outlet. A typical gas meter may include a multiplicity of internal pressure compartments or chambers with which gas passageways are defined. The passageways are intermittently opened and closed by slide valves which may be driven by crank driven cams or other linkages. The pulsing bellows, for example, seen in U.S. Pat. No. 3,386,288 and others representative of this art, convert reciprocal motion to rotary motion. Twin chamber positive displacement meters interconnect bellows with the drive chain through flag drives or the like, to effectuate movement of the volume consumption indicator and the flow path-establishing cams.
U.S. Pat. No. 3,693,444, for example, discloses typical self stabilizing slider valves of the type activated by expanding gas meter bellows. As such slider valves open and close through reciprocal motion to expose or cover up gas passageways, the gas is transmitted from the gas meter input to the gas meter output through the intermediate bellows and passages ways. U.S. Pat. No. 3,905,231, issued Sept. 16, 1975 discloses a gas activated pressure diaphragm which causes a reciprocating motion in conjunction with a flag rod. The diaphragm therein disclosed is of the pulsating gas pressurizing type. Motion transmitting linkages employed with a valve system are opened and closed in response to linkages which drive suitable covers.
As will be recognized by those skilled in the art, differential gas pressure is utilized by the bellows to provide a metering action. The diaphragms inflate or deflate periodically in response to gas pressure. Thus, each time a chamber is filled or emptied, the meter registers passed gas volumes transmitted from the input to the output (i.e. the consumer.) Bellows type gas meters are the most common in domestic and commercial gas service. These types of meters usually include a cooperative pair of spaced-apart bellows, which operate substantially simultaneously. One compartment is usually filling while the other is emptying, but all parameters are known and are substantially uniform in order to insure a reliably metered delivery of gas. The number of times each measuring chamber is filled and emptied is registered, and thus a total volume of transmitted and consumed gas is indexed. The register is usually operated by a crank which is rotated by movement of the diaphragms. Synthetic rubber diaphragms are usually used to insure that displacement is directly proportional to stroke. A plurality of sliding valves interconnected to a central crank via suitable linkages are displaced in a cam-like motion in response to bellows inflation and deflation. Meter motion usually cannot occur unless a pressure differential, and hence gas flow takes place. Nominally a pressure differential of 0.10-inch (2.5 millimeters) of water will initiate meter actuation. Usually meter capacities vary from between 150 to 17,000 cubic feet per hour. The physical dimensions, configurations, and weights of such meters of course change accordingly. While the mechanisms involved are relatively simple, a very high degree of meter accuracy is required.
Over time a variety of parts within the meter will deteriorate. Bearings can wear out, crank linkages can deform, and leaks can develop within the bellows. Numerous other problems may occur. Exposed metal surfaces, for example, may degrade in time in response to chemical actions encouraged by metal contact with gases. Usually gas meters will be replaced at least once every 10 years. The usual practice is to completely disassemble, clean, repair and recalibrate the meter. Commercial utilities such as Arkansas Louisiana Gas Company, for example, must be able to process and hence recalibrate several thousand meters per year. Gas meters are typically bulky and cumbersome to handle. The outer housing of a typical home gas meter is irregularly shaped and may range from twelve to eighteen inches high, eight to twenty inches wide, and up to eight inches deep. Such meters typically weigh from Six to Twenty Five pounds. "Wet" type flowmeters may be much bulkier and heavier, since their inner chamber is filled with liquid. The precision linkages within the component must be isolated and safety-sealed to prevent unauthorized access to the internal workings. The fact that meter housings are sealed together greatly complicates subsequent testing or repairing of such equipment.
Routine maintenance, testing, and repair require that the meter housing be opened to permit access to the interior. It is extremely difficult to securely retain such a bulky, irregularly shaped gas meter in position upon a worktable or similar supporting surface. Moreover, once positioned with known conventional equipment, the meter cannot conveniently be moved and manipulated as required for testing, repairs, or replacement of internal working parts. To properly test or gauge the meters, for example, it is necessary to position the gas meter to permit the repairman to view both the interior and the indicating dials on the front. Hence, it is necessary and desirable to provide some means for securely retaining a gas meter in position during repairs, while readily allowing and facilitating relatively easy adjustments of the meter position or orientation.
A wide variety of vises have been suggested in the past. The most representative prior art know to us is the repair rack apparatus disclosed in U.S. Pat. No. 2,621,400, issued to C. D. Peterson, on Dec. 16, 1952. This now-ancient device has been commercially marketed successfully in the past by Universal controls Corporation. The prior art rack described essentially comprises a stationary frame which mounts a rotatable, meterreceptive cradle. A meter to be serviced is locked into position within the cradle by a manual clamp, and constant adjustments to the clamping apparatus are normally required. The cradle is secured by worm-driven clamp adapted to be manually adjusted to orient the meter device. When the meter is thus secured, the cradle may be rotated until the meter is disposed in a desired position for repair. A threaded retainer rod must then be manually tightened to hold the cradle in the desired position during use. While this device has found widespread commercial acceptance, it is slow and cumbersome in use. Time consuming, manual adjustments are repeatedly required at the individual work/repair station to successively receive and secure meters of varying sizes, shapes and configurations.
The rotatable vise described in U.S. Pat. No. 2,722,147 issued Nov. 1, 1955 comprises a closed clamp, the jaws of which are operatively linked by a rotatable, threaded rod. The jaws may be selectively opened or closed by manual adjustment of the rod to clamp the meter to be repaired. After the jaws are tightened, the tool is manually rotated into position by manipulation of a ratchet-driven rod associated with the clamp. Another manually-driven vise of some relevance to the present invention is taught by Barton, U.S. Pat. No. 3,888,476, issued June 10, 1975. The vise is mounted upon a rotatable base and includes a pair of manually adjustable, cooperating arms. Prior art devices of less relevance to the present application include the universal vise of Disse, U.S. Pat. 2,390,428; issued Dec. 4, 1945; the quick-change vise of U.S. Pat. No. 3,520,527, issued July 14, 1970 to Persson; and the work-holding stand described by Hille in U.S. Pat. No. 2,815,566 issued Dec. 10, 1957.
U.S. Pat. No. 2,054,572 issued Sept. 15, 1936 to McKenna discloses a toggle-type clamp involving an over center action, and is representative of the type of bracing and clamping mechanisms employed in conjunction with known repair vises. U.S. Pat. No. 2,456,100 also discloses a toggle clamp suitable for use in prior art workpiece holding equipment.
U.S. Pat. Nos. 2,815,566 and 1,600,835 are representative of prior art stands broadly related to the servicing of workpieces or equipment. U.S. Pat. No. 1,860,844 issued May 31, 1932 discloses a wheeled carriage adapted to secure a workpiece. U.S. Pat. No. 2,431,589 discloses a propeller stand. Vises for handling parts and rotating them into different positions are seen in U.S. Pat. Nos. 3,520,527 and 2,431,589.
However, none of the prior art retainer devices known to us provides an automatic system for quickly and reliably grabbing and retaining meters of varying configurations. Moreover, none of the prior art vises or test stands known to us provide satisfactory safety or locking mechanisms which firmly secure the meter in position substantially irregardless of the width of the meter.